JERUSALEM, April 28 (Reuters) - A former Israeli spymasterhas branded the country's leaders unfit to tackle the Iraniannuclear programme and "messianic" in the strongest criticismfrom a security veteran of threats to launch a pre-emptive war.

Other veterans have come out against Prime Minister BenjaminNetanyahu and Defence Minister Ehud Barak.

But the censure from Yuval Diskin, who retired as head ofthe Shin Bet domestic intelligence service last year, wasespecially strong and unusual in using the language of religiousfervour that Israelis associate with Islamist foes.

"I have no faith in the prime minister, nor in the defenceminister," Diskin said in remarks broadcast by Israeli media onSaturday. "I really don't have faith in a leadership that makesdecisions out of messianic feelings."

The Prime Minister's Office and Defence Ministry had noimmediate response to Diskin's remarks. But Foreign MinisterAvigdor Lieberman rebuked Diskin and questioned his motives.

The catastrophic terms with which Netanyahu and Barakdescribe the prospect of a nuclear-armed Iran have stirredconcern in Israel and abroad of a possible strike against itsuranium enrichment programme. Iran says the project is entirelypeaceful and has promised wide-ranging reprisals for any attack.

World powers, sharing Israeli suspicions Iran has a covertbomb-making plan, are trying to curb it through sanctions andnegotiations. Those talks resume in Baghdad next month, butBarak on Thursday rated their chance of succeeding as low.

Although Israel has long threatened a pre-emptive strike ifdiplomacy fails, some experts believe that could be a bluff tokeep up pressure on the Iranians, making it harder to interpretthe swirl of comments from the security establishment.

In a commentary on Diskin's remarks, Amos Harel of theliberal newspaper Haaretz wrote that the temperature was risingahead of the nuclear talks.

"Nothing has been determined in the Iranian story, and thespring is about to boil over into another summer of tension," hewrote.

FALSE IMPRESSION

Diskin spoke days after Israel's top military commander,Lieutenant-General Benny Gantz, told Haaretz he viewed Iran as"very rational" and unlikely to build a bomb, comments thatapparently undermined the case for a strike.

The former Shin Bet chief was specifically damning ofNetanyahu and Barak, who have often crafted strategy alone andwhose rapport dates back four decades to when they servedtogether in a top-secret commando unit.

"They're creating a false impression about the Iranianissue," Diskin told a private gathering on Friday, where thecomments were recorded. "They're appealing to the stupid public,if you'll pardon me for the phrasing, and telling them that ifIsrael acts, there won't be an (Iranian) nuclear bomb."

Diskin said he was not necessarily opposed to an attack onIran, though he cited experts who argue this risked backfiringby accelerating its nuclear programme.

Netanyahu's former Mossad foreign intelligence director,Meir Dagan, last year also ridiculed the Israeli war option.

Diskin went a step further by saying that Netanyahu andBarak were not up to the job of opening an unprecedented frontwith Iran and, potentially, with its allies on Israel's borders.

Netanyahu is a second-term premier with solid publicapproval ratings and a broad conservative coalition. Barak, aformer prime minister, is Israel's most decorated soldier.

"I have seen them up close," Diskin said. "They are notmessiahs, the two of them, and they are not people who Ipersonally, at least, trust to be able to lead Israel into anevent on such a scale, and to extricate it."

Foreign Minister Lieberman said questions such as how and ifto tackle Iran "are not made by the prime minister and defenceminister. They are usually made in the security cabinet orcabinet."

Lieberman suggested to Israel's Channel Two television thatDiskin might be angry at being passed over for the job as headof the Mossad.